Photoflash lamp



y 1962 D. Y. BROUSE ETAL 3,045,460

PHOTOFLASH LAMP Filed April 27, 1960 MILLISECONDS 9 g 1 MILLISECONDS DAVID Y. BROUSE EUGENE W. DESAULNIERS JR.

INVEN RS LUMENS AT ORNEY United States Patent 3,045,460 PHOTUFLASH LAMP David Y. Brouse and Eugene W. Desaulniers, Jr., Williamsport, Pa., assignors to Sylvania Electric Products Inc., a corporation of Delaware Filed Apr. 27, 1960, Ser. No. 25,055 6 Claims. (Cl. 67-31) This invention relates to the manufacture of photoflash lamps and more particularly to the manufacture of photoflash lamps in which the gas fill pressures are several atmospheres.

Over the years, most of the commercial photofiash lamps, particularly those used by amateur photographers, have been characterized by the use of shredded aluminum foil as the combustible and oxygen, at pressures below atmospheric, as the combustion-supporting gas. In the manufacture of these lamus, it has been known that the time for the light output to reach its peak intensity may be readily controlled by adjustments in the primer applied to the ends of the lead-in wires and/ or increasing or decreasing the cross section of the shredded aluminum foil. However, it has been found that as the oxygen pressure is increased, the accuracy and uniformity of these timing controls decrease. In lamps containing oxygen at pressures of at least several atmospheres, these timing controls are no longer effective from a practical viewpoint.

It has been suggested that timing control may be obtained in lamps with pressures above atmospheric by utilizing a mixtureof nitrogen and oxygen as the combustion-supporting gas. Although this enabled the attainment of a definite retardation in the time to reach peak light output, the addition of nitrogen to lamps using shredded aluminum foil as the combustible caused a severe loss in the total light output obtained.

Recently, there has been made available commercially, photoflash lamps in which the combustible is shredded zirconium foil and. the combustion-supporting gas is at pressures substantially above atmospheric. The principal object of this invention is to provide a reliable means for obtaining the desired timing control in lamps of this type without causing any substantial loss in total light output obtained. In accordance with the principles of our invention, this principal object is attained by using a combusion-supporting gas comprising a mixture of oxygen and about 1% to about 10% by volume of nitrogen. We have found that beneficial effects are obtained within this range. Below 1%, the nitrogen does not appear to give any substantial beneficial effect. Above 10%, a tendency toward an appreciable loss in total light output is noted. As will be apparent from the description below and an examination of the accompanying drawing, very favorable results are obtained when about nitrogen is used.

In the accompanying drawing,

FIGURE 1 is a plot of light output in terms of lumens against time in terms of milli-seconds of a flash lamp of the type shown in FIGURE 3 in which oxygen alone is the combustion-supporting gas.

FIGURE 2 is a plot of light output in terms of lumens against time in terms of milliseconds of a flash lamp of the type shown in FIGURE 3 in which the combustionsupporting gas is about 95% oxygen and 5% nitrogen, by volume.

FIGURE 3 is an elevational view of one type of photoflash lamp with which this invention may beemployed.

Referring first to FIGURE 3, the photoflash lamp therein illustrated comprises a sealed, light-transmitting envelope 1 within which a quantity of shredded zirconium foil 3 is disposed. The envelope 1 is also provided with a filling of combustion-supporting gas, which will be described more in detail below. A tungsten filament 5 is disposed within the envelope 1 and is attached to lead-in wires 7 and 9 which are supported by and extend through insulator button 8. The inner ends of the lead-in wires 7 and 9 may be provided with a quantity of ignition paste The lead-in wires 7 and 9 extend through an end of the lamp envelope and are bent into the form of stirrups 13 and 15 lying along opposite sides of the press 17, the wires finally re-entering the press 17 some distance away from the points at which they emerge. The stirrups 13 and 15 define electrical contact members for engagemeant with electrical contact members of a flash gun.

The tubular lamp envelope is a T3- /z bulb type provided with a filling of about 30 mgs. of shredded zirconium foil preferably having a cross-section of between about 0.5x 10* sq. in. to about 2.0 1()- sq. in. When provided with a gas filling of oxygen at about six atmospheres pressure, for example, with the foil and the gas substantially in stoichiometric balance, the light output of such a lamp when flashed is substantially as shown in FIGURE 1. When provided with about oxygen and about 5% nitrogen at about six atmospheres pressures, with the foil and the gas substantially in stoichiometric balance, the light output of such a lamp when flashed is substantially as shown in FIGURE 2. Two major differences between these two curves will be readily apparent, viz., in FIGURE 2, the peak time is delayed and a flatter, longer light output characteristic is obtainedand both of these desirable results are obtained with no substantial loss in total light output. This result is quite unexpected in view of the prior experience described above in connection with flash lamps employing shredded aluminum foil as the combustible.

It will be noted that the FIGURE 1 lamps have a peak time ofabout 10 to 11 milliseconds. Primer head size and primer form'ula variations had little or no effect on retarding peak time except that there was some indication that it may have contributed to narrowing the spread of peak times from lamp to lamp. As a matter of fact, insofar as its effect on control of peak time is concerned, it didnt seen to make any substantial difference whether or not any primer was used.

On the other hand, it will be noted that the FIGURE 2 lamps have a peak time of about 14 to 15 milliseconds with no substantial loss in light output. It will also be noted that another significant advantage is obtained with the FIGURE 2 lamps. In addition to delaying the time to peak light output, the peak is lowered without any substantial loss in total light output, thus providing a flatter, longer, useful light output characteristic which makes synchronization with camera shutters much less critical. This increase in the duration of useful illuminat-ion makes a lamp of this type ideal for use with focal plane cameras which usually require a fairly high level of illumination for a period of about 15 milliseconds since the curtain type shutter traverses the film plane during this time interval.

What we claim is: t

1. A photoflash lamp comprising: a sealed light-transmitting envelope; a quantity of filamentary zirconium in said envelope; ignition means disposed in said envelope in operative relationship with respect to said filamentary zirconium; and a gas filling in said envelope at a pressure above atmospheric, said gas filling comprising oxygen and about 1% to about 10% by volume of nitrogen.

2. A photoflash lamp comprising: a sealed light-transmitting envelope; a quantity of filamentary zirconium in said envelope; ignition means disposed in said envelope in operative relationship with respect to said filamentary zirconium; and a gas filling insaid envelope at a'pressure above atmospheric, said gas filling comprising oxygen and about 1% to about 10% by volume of nitrogen, the ratio between said filamentary zirconium and the weight a) of said gas being substantially in stoichiometric balance.

3. A photofiash lamp comprising: a sealed light-transmitting envelope; a quantity of filamentary zirconium in said envelope; ignition means disposed in said envelope in operative relationship with respect to said filamentary zirconium; and a gas filling in said envelope at a pressure of at least several atmospheres, said gas filling comprising about 95% oxygen and about 5% nitrogen by volume.

4. A photoflash lamp comprising: a sealed light-transmitting envelope; a quantity of filamentary zirconium having a cross-section of between about 0.5 X sq. in. to about 2.0x 10 sq. in., disposed in said envelope; ignition means disposed in said envelope in operative relationship with respect to said filamentary zirconium; and a gas filling in said envelope at a pressure above atmospheric, said gas filling comprising oxygen and about 1% to about 10% by volume of nitrogen.

5. A photofiash lamp comprising: a sealed light-transmitting envelope; a quantity of filamentary zirconium, having a cross-section of between about 0.5 10 sq. in. to about 2.0 10 sq. in., disposed in said envelope in operative relationship with respect to said filamentary zirconium, and a gas filling in said envelope at a pressure above atmospheric, said gas filling comprising about oxygen and about 5% nitrogen by volume, the ratio between said filamentary zirconium and the weight of said gas being substantially in stoichiometric balance.

6. A photofiash lamp comprising: a sealed light-transmitting enevelope; a quantity of filamentary zirconium in said envelope; ignition means disposed in said envelope in operative relationship with respect to said filamentary Zirconium; and a gas filling in said envelope at a pressure of at least several atmospheres, said gas filling comprising about 95% oxygen and about 5% nitrogen by volume, the ratio between said filamentary zirconium and the Weight of said gas being substantially in stoiehiometric balance.

References Cited in the file of this patent UNITED STATES PATENTS 2,272,059 De Margitta Feb. 3, 1942 2,315,099 Van Liempt Mar. 30, 1943 2,865,186 Anderson et al ec. 23, 1958 2,955,447 Fink et al. Oct. 11, 1960 2,982,119 Anderson May 2, 1961 I 

1. A PHOTOFLASH LAMP COMPRISING: A SEALED LIGHT-TRANSMITTING ENVELOPE; A QUANTITY OF FILAMENTARY ZIRCONIUM IN SAID ENVELOPE; IGNITION MEANS DISPOSED IN SAID ENVELOPE IN OPERATIVE RELATIONSHIP WITH RESPECT TO SAID FILAMENTARY ZIRCONIUM; AND A GAS FILLING IN SAID ENVELOPE AT A PRESSURE ABOVE ATMOSPHERIC, SAID GAS FILLING COMPRISING OXYGEN AND ABOUT 1% TO ABOUT 10% BY VOLUME OF NITROGEN. 